Simulation of the Effect of Inlet Blocking on NO Formation in a Swirl Coal Combustor

To develop low-pollution burners, the effect of inlet blocking on NO formation in a swirl coal combustor is studied by numerical simulation. An algebraic unified second-order moment turbulence-chemistry model and a simplified Solomon model of HCN release for NO formation are proposed. These models are incorporated into a full two-fluid model of reacting gas-particle flows and coal combustion. The sub-models are the k-ε-kp two-phase turbulence model, the EBU-Arrhenius volatile and CO combustion model, the six-flux radiation model, coal devolatilization model and char combustion model. The effect of inlet blocking position on NO formation in a swirl coal combustor is studied. The predicted temperature, turbulence intensity, coal concentration and NO concentration were obtained. The prediction results for typical cases are in good agreement with the experimental results reported in references, indicating that the numerical models are appropriate. The prediction results indicate that the blocking between the primary-air flow and the secondary-air flow will increase the turbulence intensity, but increase the coal concentration and reduce the temperature in the near-inlet zone, hence can remarkably reduce the NO formation.